I have 2 kids who are vegan/vegetarian. So at family gatherings I have to come up with recipes that can be adapted to their vegetarian lifestyle. This is one of those recipes. We had this at Christmas and it was a big hit.
Roast the parsnips, turnips and carrots at 350 degrees with a little olive oils or 20 min. In a large frying pan melt butter and saute onions, mushrooms , and celery for 8 min on medium heat.
Add flour, salt and pepper and cook for 1 min stirring constantly. Add the beer scrapping up the bits on the bottom of the pan. when thickened, add vegetable broth and simmer until the sauce has the desired thickness, about 5 min.
Add roasted vegetables and peas. Put mixture in a baking dish and top with mashed potatoes. Dot with butter. Bake at 350 degrees for 30 min.